major DNS hiccup

This was all working fine until this afternoon - when I did nothing and it just decided to malfunction.

Running 6.1, with named, which also acts as master for a private TLD behind a firewall. Configuration files untouched for a year or more, been working fine since the upgrade to 6.1 a month or two back.

Today, I suddenly found that DNS responses from the net often look wrong. Using ethereal, I see that returned DNS answer packets often come back with success, but no result records, which isn't good news. Sometimes ethereal flags a 'format error', whatever that is; such packets still have no results, and also no question either. The private TLD works fine - it's only stuff from the net that's affected, but /not/ everything.

sockstat reports named is running with port 53 open on various addresses. I've restarted named and even rebooted to no avail.

If I remove 127.0.0.1 from resolv.conf, and replace with my ISP's name servers, DNS from the net at large works just fine (although obviously my private TLD now fails).

On the offchance the problem was the NIC to the cable modem, I've changed that; no joy though. Anyway, if there were a bad fault there, I'd expect to see other problems as well.

This one seems to fall heavily into the "can't happen" category, and I'm stuck for ideas: would /very/ much appreciate pointers about where to look.

Thanks in advance.

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Mike Scott Harlow Essex England.(unet -a-t- scottsonline.org.uk)
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